Apparatus for the control of repetitive events dependent on operating parameters of internal combustion engines

ABSTRACT

Control signals for triggering the events to be controlled, via at least one output stage (13, 14), are generated in a vehicular computer (11) as a dependent function of the output signals of a sensor (10) coupled to a rotating shaft of the engine, and of further sensors dependent on other operating parameters. At least one sensor-controlled auxiliary control device (17, 18) is provided. The output signals of the auxiliary control devices (17, 18) are transmitted via a switching device (12) to the terminal control stages (13, 14) as an alternative to the output signals of the computer (11). The switching device (12) is preferably embodied as a multiplexer and is controllable by an error decoding stage (19) for decoding and monitoring serial, or parallel, signals of the computer (11) to determine proper function of the computer (11); in case of malfunction of the computer (11), decoding stage (19) causes control of the output stage, or stages (13, 14) from the respective auxiliary control device.

The invention relates to an apparatus for the control of repetitiveevents dependent on the operating parameters of combustion engines,especially for automotive use. Typical controlled events are ignition,fuel injection, transmission shifting.

BACKGROUND

Programmable or non-programmable computer apparatus to control operatingevents in vehicles and engines therefor are well known, for example fromthe W. German Pat. No. 2 504 843 (to which U.S. Pat. No. 4,063,539corresponds), the W. German published application DE-OS 25 39 113 andthe W. German laid-open application DE-OS 2,655,948 (to which U.S. Pat.No. 4,174,688 corresponds). Such computers, having many components, havecomplex structures and hence are subject to a variety of possibilitiesfor error. An error which, in itself, is insignificant can neverthelesslead to the breakdown of the system to be controlled, and can immobilizethe internal combustion engine, or the vehicle driven by the engine.

THE INVENTION

It is an object to provide a system which detects errors in theoperation of computers, and particularly on-board vehicular computersand, upon detection of such errors, causes transfer of operation fromcomputer control of the internal combustion engine of the vehicle sothat total breakdown of the vehicle will not result; continued operationwill, at least, permit driving the vehicle to a repair station.

Briefly, an on-board vehicle computer is provided, connected to receiveinput data from a sensor coupled to the crankshaft of an engine and, ifdesired, additional input data relating to operating parameters of theengine, such as temperature, pressure, and the like, in short, toreceive operating signals. The computer processes these operatingsignals in accordance with a program stored therein to provide outputsignals to control at least one of: ignition events, fuel injectionevents and, if desired, gear shifting and the like. The system,additionally, includes an auxiliary ignition and, if provided, anauxiliary fuel injection control apparatus, merely connected to thespeed transducer. In the most simple form, the speed transducer can bebreaker points of an ignition system, or may be a non-contactingignition system transducer. The auxiliary control units provide outputsignals to a transfer switch which transfers the signals from theauxiliary unit to the respective ignition or fuel injection outputstages, for example to the ignition coil, rather than the output signalsfrom the on-board vehicle computer, if a malfunction in the computer isbeing sensed. Malfunction in the computer is sensed in an error decodingstage which includes a logic circuit testing the signal output from thecomputer with respect to a built-in logic and determining if the signaloutput from the computer meets certain predetermined criteria. If itdoes, the transfer switch is set in "normal" position, and the computercontrols operation of the respective output units, such as an ignitionsystem, an automatic gear change system, or the like. If, however,deviation of the signals from the computer with respect to the criteriastored in the error decoding stage is sensed, the switch transferscontrol of the ignition and/or fuel injection system over to theauxiliary control units to permit continued operation although not asfinely tuned as provided by the on-board vehicle computer. Yet, thecontinued operation permits the user to continue to operate the vehicleand, if necessary, drive to a repair or service station. Malfunction ofthe computer is also indicated in an indicator.

The error decoding stage may have certain hierarchies of detection--forexample to detect serious errors which will definitely and grosslyinterfere with vehicle operation--in which case the switch-over from theauxiliary control system is commanded; or to detect lesser errors, onlyaffecting, for example, most efficient operation, in which case noswitch-over is controlled but only an indication of the error detectionis provided, in order to warn the driver that the vehicle or the engineis not operating under intended and optimum conditions but, rather, thata malfunction has occurred.

The apparatus according to the invention, with the distinguishingfeatures of the main claim, has the relative advantage that even uponbreakdown of the computer, essential functions are maintained to such anextent that the operation of the internal combustion engine or,respectively, of the vehicle, is still possible.

The apparatus according to the invention is can be constructed with fewcomponents, or the functions may even be integrated within the computer.

Especially safe error recognition is achieved by constructing the errordecoding stage, connected to the computer for the serial decoding ofsignal sequences, as a register; the register contents are periodicallyinterrogated. Error annunciation and no-error annunciation, are realizedby means of coded serial signal trains, resulting in maximum reliabilityin error recognition. Preferably, a multiplexer serves as the switchingdevice to switch from the computer to the auxiliary control device. Uponrecognition of an error, an indicator device is activated; this forms afurther refinement of the invention.

DRAWING

FIG. 1: A block circuit diagram of a first exemplary embodimentutilizing serial decoding;

FIG. 1a: A fragmentary diagram of the circuit of FIG. 1 and illustratingparallel decoding;

FIG. 2: A refinement of an error decoding stage, and;

in FIG. 3: A signal diagram illustrating the functioning of the circuitdepicted in FIG. 2.

DESCRIPTION OF THE EXEMPLARY EMBODIMENT

In the exemplary embodiment depicted in FIG. 1, a sensor 10 is connectedto a computer 11. Such a sensor installation 10 commonly consists of asensor disk 100 preferably coupled to the crankshaft of an internalcombustion engine. Reference marks 101 are affixed to the sensor disk100 and pass a receiver or pick-up 102 where they generate a signalserving for the transmission of speed information and of angularposition information. The generation of such a signal can take placeinductively, optically, or by means of the Hall effect or of the Wiegandeffect. The signal from pick-up 102 is connected to a computer 11. Thecomputer 11 itself can be constructed as a hardwired (non-programmable)computer or as a programmed computer. Additional sensing inputs 11a,11b, supply operation signals, like load, pressure (see, for example,the referenced U.S. Pat. No. 4,063,539). Two control outputs of thecomputer 11 are connected to two terminal or output control stages 13,14 via a switching device 12 embodied, for example, as a multiplexer. Asuitable multiplexer is, available commercially, e.g. as IC integratedcircuit (IC) type 4016. The terminal control stage 13 is shown as anignition stage. Commonly, it has an ignition coil, whose primary circuitcontains a switching transistor and whose secondary circuit contains atleast one spark plug 15. The terminal control stage 14 is shown as afuel injection stage which controls fuel injection processes. This stage14 includes, essentially, an amplifier stage controlling injectionvalves 16. A system 10 to 16--with the exception of the switching device12--is known from the prior art cited above, and is described there ingreater detail.

Further terminal stages could also be controlled by means of thecomputer 11, for example, further terminal ignition stages could beemployed to obtain high voltage distribution to several cylinders of aninternal combustion engine without mechanically operating components.Output stages for transmission control can also be connected to thecomputer 11.

The output of the sensor installation 10 is further connected to theswitching inputs of the switching device 12 via two auxiliary controldevices 17, 18. The auxiliary control device 17 is used for emergencycontrol of the ignition stage 13, and the auxiliary control device 18 isused for emergency control of the injection stage 14. Such auxiliarycontrol devices can be embodied, in the simplest case, as timingelements whose holding time determines the closure time of theelectrical switch for the ignition, and which determines the injectionduration fuel injection. Instead of these simplest versions, somewhatmore expensive devices can also be employed to serve the emergencyfunction, e.g. as described in the W. German publications DE 2 640 791or DE 2 700 676 (to which U.S. Pat. Nos. 4,133,323 and 4,212,280correspond).

The computer 11 is connected to the switching control input of theswitching device 12 via an error decoding stage 19.

Operation

During disturbance-free operations, the switching device 12 is switchedby the error decoding stage 19 so as to let the computer 11 control theterminal stage 13, 14. If an error now appears in the computer 11,resulting either in a false or absent output signal, the error decodingstage 19 responds and flips the switching device 12 into its secondinterconnecting state, whereby the terminal stages 13, 14 are connectedto the auxiliary control devices 17, 18. The indicator device 20 isactuated simultaneously. The ignition and injection processes are nowbeing controlled by the auxiliary control devices 17, 18. This type ofcontrol may result in reduced running comfort of a motor vehicle, butwill guarantee that the vehicle can proceed to a repair shop.

In place of a common switch-over of all of the control processes to theauxiliary control devices, it is possible to provide for separateswitching in the sense that only the section in which a malfunctionappears is switched to the auxiliary mode. Several error decoding stageswould be required in that case.

For serial data admission, the error decoding stage 19 can consist, inthe simplest case, of a retriggerable timing element. The computer 11normally delivers a periodic signal train representing the correctfunction. The maximum gap between signals must then be shorter than thetiming duration or holding time of the timing element 19, so that thetiming element never flips back during normal, i.e. proper operation.Only when a signal is missing, will a flip-back occur, therebytriggering the switchover to the auxiliary control device.

A parallel error signal can also be used instead of a serial errorsignal. In that case, the error decoding stage 19 must be constructed asa logical network 19a--see FIG. 1a, in particular as a logical gatingcircuit. Input is by a parallel input bus or cable 21a. In accordancewith any given computer system, conditions can be set up which mustappear periodically and simultaneously. When all of the conditions aremet simultaneously, as determined by timing applied by clock terminal29a, for example, at terminal 30', an output signal which characterizesthe proper functioning of the system, is produced by the logiccircuitry. If one of the conditions is not met, the complementary outputsignal at terminal 30 characterizing an error function is produced. Suchan error signal can, if necessary, be stored in a flipflop 32 serving asan intermediate memory or buffer store.

An preferred embodiment of an error decoding stage 19 for serialdecoding of signal trains is shown in FIG. 2. The input terminal 21 ofthe error decoding stage 19, is connected to the output of the computer11. The terminal 21 is connected to the input of a first flipflop 22; tothree further flipflops 23 to 25 are serially interconnected to theoutput of flipflop 22. The output of each flipflop is connected to theinput of the next flipflop. The output of the flipflop 22 is furtherconnected via an inventer 26 to the input of an AND-gate 27 whose otherinputs are connected to the input of the remaining flipflops 23 to 25.The output of the AND-gate 27 is connected to the reset input R of adigital counter 28. A terminal 29 carrying a clock pulse train isconnected to the clock (clock) inputs of the flipflops 22-25 and also tothe clock (clock) input of the counter 28. An output of the counter 28is connected to an output connector 30 and also to a blocking or enableinput E of this counter 28.

Operation, with reference to FIG. 3

The signal identifications relate to similarly identified terminal or tooutputs of similarly identified construction components.

It is assumed that the signal sequence U21 supplied by the computer 11at terminal 21 is formed in such a way that a signal U21 is presentduring the occurrence of three pulses of a pulse signal U29 (see FIG.3), and that the signal U21 is absent during the subsequent pulse signalU29. The signals U21 are shifted through the flipflops 22 to 25 at therhythm of the pulse or clocking frequency. With each fourth pulse signalU29, an 0-signal is thus present at the output of the flipflop 22 and a1-signal is present at the output of each of the remaining flipflops 23to 25. The inverter 26 thus produces the AND-condition for the AND-gate27, resulting in a reset signal U27. Hence, the counter 28 countscyclically up to the numeral three, after which the counter 28 is reset.In that case, the third lowest output (2²) is chosen as the output ofthe counter 28, corresponding to a binary 4. Because the number four isnot reached in this way, a continuous 0-signal is present at theterminal 30 causing the output stages 13, 14 (FIG. 1) to be connected tothe computer 11 via the switching device 12.

The illustration is drawn to an error in the third cycle. As illustratedin FIG. 3, and this condition is manifested by an altered signalsequence U21. For the fourth signal pulse, the AND-condition for theAND-gate 27 is not met, and no reset signal is produced for the counter28. Therefore, the counter 28 counts to the value four, which causes a1-signal to appear at the output terminal 30 and causes the counter 28to be blocked by the blocking input E for any subsequent counting cyclesuntil a reset signal once again appears. This 1-signal present at theterminal 30 is the decoded error signal which activates the switchingdevice 12 (FIG. 1) and causes a switchover of control of the terminalstages 13, 14 from the auxiliary control stages 17, 18.

Instead of the signal sequence U21, any other suitable signal train canbe accommodated, and may, if necessary, be decoded by means of longerchains of flipflops and by a correspondingly modified logicalinterconnection of some of the outputs.

Instead of the single mounitoring function supervising operation of thecomputer, supplementary monitoring of further construction componentscan also be provided. Signals could be selected whose presence indicatesa definite signal combination or a particular status in the computer.Such signals can then be interconnected according to the precedingdescription.

Further error decoding stages 19 can be employed to decide if the givenerror is serious enough to require a switchover to the emergency systemprovided by the auxiliary systems 17, 18, or whether it is sufficientmerely to indicate the error to the operator without carrying out aswitchover to the emergency system in switching unit 12.

What is claimed is:
 1. Apparatus for controlling repetitive eventsdependent upon operating parameters of a vehicular internal combustionengine, and including at least one of:ignition events; fuel injectionevents; transmission events, comprising a vehicular computer (11); means(11a, 11b) applying vehicle operation signals to the computer; an enginerotation sensor (10) coupled to a rotating shaft of the engine, saidsensor being connected to and applying engine rotation signals to thecomputer, the computer generating control signals in dependence on thesignals applied thereto in accordance with a program stored therein; atleast one output control stage (13, 14) for triggering the event orevents to be controlled; at least one auxiliary control device (17, 18)connected to the engine rotation sensor and receiving the enginerotation signals; a controllable switching device (12) having its outputconnected to the input of the at least one output control stage (13, 14)and inputs, respectively, connected to the output of the computer (11)and to the auxiliary control device, or devices (17, 18) and operativeto selectively switch the output to one of the inputs; an error decodingstage (19) connected to the computer, said error decoding stageincluding a clock source (29); a shift register (22, 23, 24, 25)serially decoding signal sequences applied to the error decoding stageby the computer, and logic means (28) connected to the register, theregister being periodically interrogated if the contents thereof matchthe logic conditions determined by the logic means.
 2. Apparatusaccording to claim 1, wherein the logic means comprises a counter. 3.Apparatus according to claim 1, wherein the controllable switchingdevice comprises a multiplexer.
 4. Apparatus according to claim 1,further including an error indicator (20) connected to the errordecoding stage and furnishing an error output indication if the errordecoding stage determines that the signals applied thereto from thecomputer (11) are improper.